Microelectronic package and method of manufacture thereof

ABSTRACT

A microelectronic assembly may include a substrate having an opening extending between first and second oppositely facing surfaces of the substrate, the opening elongated in a first direction; and at least one microelectronic element having a front face facing and attached to the first surface of the substrate and a plurality of contacts at the front face overlying the opening, the microelectronic element having first and second opposite peripheral edges extending away from the front face. The first peripheral edge extends beyond, or is aligned in the first direction with, an inner edge of the opening, and the opening extends beyond the second peripheral edge.

CROSS-REFERENCED TO RELATED APPLICATIONS

The present application is a Divisional of U.S. application Ser. No.13/746,571, filed Jan. 22, 2013, the disclosure of which is incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates to microelectronic packages and methods oftheir manufacture.

BACKGROUND OF THE INVENTION

Microelectronic elements such as semiconductor chips commonly areprovided with elements which protect the microelectronic element andfacilitate its connection to other elements of a larger circuit. Forexample, a semiconductor chip typically is provided as a small, flatelement having oppositely facing front and rear surfaces and contacts atthe front surface. The contacts are electrically connected to thenumerous electronic circuit elements formed integrally within the chip.Such a chip most commonly is provided in a package having a miniaturecircuit panel referred to as a substrate. The chip is typically mountedto the substrate with the front or rear surface overlying a surface ofthe substrate, and the substrate typically has terminals at a surface ofthe substrate. The terminals are electrically connected to the contactsof the chip. The package typically also includes some form of coveringoverlying the chip on the side of the chip opposite from the substrate.The covering serves to protect the chip and, in some cases, theconnections between the chip and the conductive elements of thesubstrate. Such a packaged chip may be mounted to a circuit panel, suchas a circuit board, by connecting the terminals of the substrate toconductive elements such as contact pads on the larger circuit panel.

In certain packages, the chip is mounted with its front surfaceoverlying an upper surface of the substrate, whereas terminals areprovided on the oppositely facing lower surface. A mass of a dielectricmaterial overlies the chip and, most typically, the electricalconnections between the chip and the conductive elements of thesubstrate. The dielectric mass may be formed by molding a flowabledielectric composition around the chip so that the dielectriccomposition covers the chip and all or part of the top surface of thesubstrate. Such a package is commonly referred to as an “overmolded”package, and the mass of dielectric material is referred to as the“overmold.” Overmolded packages are economical to manufacture and thusare widely used.

In some applications, it is desirable to mount a plurality of chips 12overlying an upper surface 14 of a substrate 16 in a face downorientation, such as in a quad face down (QFD) or like orientation asshown in FIG. 1. See, for example, U.S. Pat. No. 8,338,963 issued Oct.25, 2012 and U.S. Publication No. 2013/0015591 published Jan. 17, 2013,the disclosures of which are incorporated by reference herein. The chips12 may be attached to the surface 14 by an attachment layer 18, withcontacts 22 at the front faces of the chips 12 overlying openings 20 inthe substrate 16. The openings 20 have an elongated dimension, extend tothe front face of the chip and have portions 24 at opposite ends of theelongated dimension through which dielectric material may flow from anopening in the attachment layer 18 during manufacture of themicroelectronic package. In microelectronic packages having chips in QFDand like orientations as shown in FIG. 1, the openings typically are notarranged so the elongated dimension of the openings extends in a samelongitudinal direction, as is customary when chips are arranged in asingle or dual face down orientation in a microelectronic package.During manufacture of such packages, when encapsulant material isprovided to encapsulate the elements of the package, which includesfilling the openings with the encapsulant material, the material istypically flowed from a molding tool 30 in a single direction X over thetop surface or attachment layer 18 side of the substrate 16. In QFD orlike orientations, the openings 20 that extend in a longitudinaldirection transverse, such as perpendicular, to the encapsulant materialflow direction X may not become completely filled by the encapsulantmaterial, because voids at which air is entrapped may form within theopenings, which is undesirable.

Despite the considerable effort devoted in the art to development ofmicroelectronic packages having multiple electronic elements, furtherimprovement would be desirable.

SUMMARY OF THE INVENTION

In accordance with one embodiment, a microelectronic assembly mayinclude a substrate having an opening extending between first and secondoppositely facing surfaces of the substrate, the opening elongated in afirst direction; and at least one microelectronic element having a frontface facing and attached to the first surface of the substrate and aplurality of contacts at the front face overlying the opening, themicroelectronic element having first and second opposite peripheraledges extending away from the front face, where the first peripheraledge extends beyond, or is aligned in the first direction with, an inneredge of the opening, and where the opening extends beyond the secondperipheral edge.

In accordance with another embodiment, a method of forming amicroelectronic assembly may include joining a substrate with amicroelectronic element, the substrate having an opening extendingbetween first and second oppositely facing surfaces of the substrate,the opening elongated in a first direction, and the microelectronicelement having a front face facing and attached to the first surface ofthe substrate and a plurality of contacts at the front face overlyingthe opening, the microelectronic element having first and secondopposite peripheral edges extending away from the front face, where thefirst peripheral edge extends beyond, or is aligned in the firstdirection with, an inner edge of the opening, and where the openingextends beyond the second peripheral edge.

In accordance with another embodiment, a microelectronic assembly mayinclude a substrate having an opening extending between first and secondoppositely facing surfaces of the substrate, the opening elongated in afirst direction; and a microelectronic element having a front facefacing and attached to the first surface of the substrate and aplurality of contacts at the front face overlying the opening, themicroelectronic element having first and second opposite peripheraledges extending away from the front face, where the opening extendsbeyond at least one of the first or second peripheral edges, and whereat least one of the first surface or the second surface of the substratepartially defines at least one vent extending from the opening.

In accordance with another embodiment, a method of forming amicroelectronic assembly may include joining a substrate with amicroelectronic element, the substrate having an opening extendingbetween first and second oppositely facing surfaces of the substrate,the opening elongated in a first direction, the microelectronic elementhaving a front face facing and attached to the first surface of thesubstrate and a plurality of contacts at the front face overlying theopening, the microelectronic element having first and second oppositeperipheral edges extending away from the front face, where the openingextends beyond at least one of the first and second peripheral edges,and where at least one of the first surface or the second surface of thesubstrate partially defines at least one vent extending from the openingbeyond a peripheral edge of the microelectronic element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of a prior art microelectronic assembly during astage in manufacturing operations thereof.

FIG. 2 is a top plan view of a portion of a microelectronic assembly ata stage in manufacturing operations, according to an embodiment of thedisclosure.

FIG. 3 is a diagrammatic sectional view of the microelectronic assemblyas shown in FIG. 2 at cross-sectional line 3-3.

FIG. 4A is a perspective view of a portion of the microelectronicassembly of FIG. 2.

FIG. 4B is a perspective view of a portion of another microelectronicassembly, according to an embodiment of the disclosure.

FIG. 5 is a top plan view of the microelectronic assembly of FIG. 2 at alater stage in manufacturing operations, according to an embodiment ofthe disclosure.

FIG. 6 is a diagrammatic sectional view of the assembly of FIG. 5 atcross-sectional line 6-6.

FIG. 7 is a top plan view of a microelectronic assembly at a stage inmanufacturing operations, according to an embodiment of the disclosure.

FIG. 8 is a top plan view of a portion of the microelectronic assemblyof FIG. 7.

FIG. 9 is a diagrammatic sectional view of the assembly as shown in FIG.8 at cross-sectional line 9-9.

FIG. 10 is a top plan view of the portion of the microelectronicassembly as shown in FIG. 8 at a later stage in manufacturingoperations, according to an embodiment of the disclosure.

FIG. 11 is a diagrammatic sectional view of the microelectronic assemblyas shown in FIG. 10 at cross-sectional line 11-11.

FIG. 12 is a bottom plan view of a portion of a microelectronic assemblyat a stage in manufacturing operations, according to an embodiment ofthe disclosure.

FIG. 13 is a diagrammatic sectional view of the microelectronic assemblyas shown in FIG. 12 at cross-sectional line 13-13.

FIG. 14 is a bottom plan view of the microelectronic assembly as shownin FIG. 12 at a later stage in manufacturing operations, according to anembodiment of the disclosure.

FIG. 15 is a diagrammatic sectional view of the microelectronic assemblyas shown in FIG. 14 at cross-sectional line 15-15.

FIG. 16 is a bottom plan view of a microelectronic assembly, accordingto an embodiment of the disclosure.

FIG. 17 is a top plan view of a microelectronic assembly, according toan embodiment of the disclosure.

FIG. 18 is a bottom plan view of a microelectronic assembly, accordingto an embodiment of the disclosure.

FIG. 19 is a top plan view of a microelectronic assembly, according toan embodiment of the disclosure.

FIG. 20 is a top plan view of a portion of the microelectronic assemblyof FIG. 19.

FIG. 21 is a diagrammatic sectional view of the microelectronic assemblyas shown in FIG. 20 at cross-sectional line 21-21.

FIG. 22 is a bottom plan view of a microelectronic assembly, accordingto an embodiment of the disclosure.

FIG. 23 is a diagrammatic sectional view of the microelectronic assemblyas shown in FIG. 22 at cross-sectional line 23-23.

FIG. 24 is a diagrammatic view depicting a system in accordance with thedisclosure.

DETAILED DESCRIPTION

Referring to FIGS. 2, 3 and 4A, a microelectronic assembly 100 accordingto an embodiment of the disclosure may include a substrate 112 having afirst surface 114 and a second surface 116. The substrate 112 typicallyis in the form of a dielectric element, which is substantially flat andmay be sheet-like and thin. In particular embodiments, the dielectricelement may include one or more layers of organic dielectric material orcomposite dielectric materials, such as, without limitation: polyimide,polytetrafluoroethylene (“PTFE”), epoxy, epoxy-glass, FR-4, BT resin,thermoplastic, or thermoset plastic materials. The first surface 114 andsecond surface 116 are preferably substantially parallel to each otherand are spaced apart at a distance perpendicular to the surfaces 114 and116 defining the thickness of the substrate 112. The thickness ofsubstrate 112 is preferably within a range of generally acceptablethicknesses for the present application. In an embodiment, the distancebetween the first surface 114 and the second surface 116 is betweenabout 25 and 500 μm. For purposes of this discussion, the first surface114 may be described as being positioned opposite or remote from thesecond surface 116. Such a description, as well as any other descriptionof the relative position of elements used herein that refers to avertical or horizontal position of such elements is made forillustrative purposes only to correspond with the position of theelements within the Figures, and is not limiting.

Electrically conductive elements 118, which may include contacts orpads, traces or terminals, are at the first and second surfaces of thesubstrate 112. As used in this disclosure, a statement that anelectrically conductive element is “at” a surface of a substrateindicates that, when the substrate is not assembled with any otherelement, the electrically conductive element is available for contactwith a theoretical point moving in a direction perpendicular to thesurface of the substrate toward the surface of the substrate fromoutside the substrate. Thus, a terminal or other conductive elementwhich is at a surface of a substrate may project from such surface; maybe flush with such surface; or may be recessed relative to such surfacein a hole or depression in the substrate. In addition, as used in thisdisclosure a statement that an electrically conductive element is “at” asurface of a circuit panel, a microelectronic element such as asemiconductor chip or a like element, indicates that, when the panel orthe element is not assembled with any other element, the electricallyconductive element is available for contact with a theoretical pointmoving in a direction perpendicular to the surface of the panel orelement toward the surface of the panel or element from outside thepanel or element. Further, as used in this disclosure, a statement thata trace extends “along” a surface means that the trace extends inproximity to the surface and substantially parallel to the surface.

Traces 120 included as the conductive elements 118 may be formed asflat, thin, elongated strips of conductive material at the surface 116.In addition, contact pads 122 included as the conductive elements 118 onthe surface 116 may be connected with the traces 120 on the surface 116.

The terminals, pads or traces serving as the conductive elements 118 maybe fabricated by numerous known methods, such as by plating theterminals, pads and traces onto the surfaces 114 and 116 of thesubstrate. In one embodiment, the traces may be embedded in the surfacesof the substrate, with the surfaces of the traces lying substantiallyflush with the surfaces of the substrate. In one embodiment, theconductive elements 118 may be formed from a solid metal material suchas copper, copper, gold, nickel, or other materials that are acceptablefor such an application, including various alloys including one or moreof copper, gold, nickel or combinations thereof.

At least some of conductive elements at the surface 116 may beinterconnected with conductive elements at the surface 114. Such aninterconnection may be completed using vias (not shown) formed in thesubstrate 112 that may be lined or filled with conductive metal that maybe of the same material as the conductive elements 118.

Referring to FIG. 2, the substrate 112 may define a plurality ofelongated openings, and microelectronic elements 150, such as asemiconductor chip or a like element, may be attached to the substrateand have contacts at front faces thereof overlying the openings,respectively. In the illustrated embodiment, the substrate 112 maydefine an opening 124A extending from the first surface 114 to thesecond surface 116 and having an elongated dimension extending a lengthCH(A) in a direction L1 from a first end 126 to a second end 128 of theopening 124A which is opposite the first end 126. In addition, thesubstrate 112 may define an opening 124B extending from the firstsurface 114 to the second surface 116 and having an elongated dimensionextending a length CH(B) in a direction L2 transverse, and in oneembodiment orthogonal, to the direction L1, from a first end 130 to asecond end 132 of the opening 124B which is opposite the first end 130.In one embodiment, the openings 124 are defined by an inner edge 143 ofthe substrate 112, and the inner edge 143 includes an inner edge surface144 extending from the surface 114 to the surface 116. In otherembodiments, the inner edge surface 144 extends between the surfaces 114and 116 or from only one of the surfaces 114 and 116. Although not shownin FIG. 2, it is to be understood that the microelectronic assembly 100may include a plurality of microelectronic elements 150 overlyingopenings 124 in the substrate having elongated dimensions extending inthe directions L1 and L2, respectively.

The microelectronic elements or chips 150 may include opposite first andsecond surfaces 152, 134, and contacts 156 at the surface 152. The chips150 may be positioned in a “face-down” orientation relative to thesubstrate 112, with the surface 152 facing the surface 114 and thecontacts 156 of the chip 152 overlying a respective opening 124. In oneembodiment, the assembly 100 may include at least one chip 150A havingopposite peripheral edges 158 and 160 that extend away from the surface152, and a major dimension of the chip 150A may extend a length D1 inthe direction L1 from the edge 158 to the edge 160.

In addition, the assembly 100 may include at least one chip 150B havingopposite peripheral edges 162 and 164 that extend away from the surface152, and a major dimension of the chip 150B may extend a length D2 inthe direction L2 from the edge 162 to the edge 164. In some embodiments,the chips 150A and 150B may have major dimensions of the same length, ora configuration having the same or similar dimensions. For example, thechips 150 may have a rectangular configuration with a major dimensionextending between the opposite peripheral edges 158, 160 and 162, 164and a minor dimension extending in a direction orthogonal to thedirection the major dimension extends.

In one embodiment, the contacts 156 of the chips 150A may overlie thecorresponding openings 124A, and a single one of the edges 158 and 160,such as the edge 158, is aligned in the direction L1 with an inner edgesurface 144A′ of the substrate 112 that defines the opening 124A. Inanother embodiment, the chip 150A may overlie the corresponding opening124A, and the edge 158 may extend beyond the edge surface 144A′ in thedirection opposite to L1. In addition, a portion 125 of the opening 124Amay extend a length P beyond the edge 160 of the chip 150A in thedirection L1, where P is about 50-150 micrometers. Based on thearrangement of the chip 150A overlying the opening 124A, the chip 150Amay overlie the entirety of the opening 124A extending from the end 126in the direction L1 toward the end 128, except for the portion 125extending beyond the edge 160.

Referring to FIGS. 3 and 4A, the assembly 100 may include an attachmentlayer 180 that joins the microelectronic elements 150 with the surface114 of the substrate 112. The attachment layer 180 may be formed ofadhesive material, such as a curable adhesive or epoxy dielectricmaterial, that may be selectively deposited by printing, or formed byphotomasking and etching, on portions of the surface 114. The attachmentlayer 180 may include opposite first and second surfaces 182, 184, wherethe first surface 182 faces the surface 114 and the second surface 184faces the surface 152 of the chip 150.

In one embodiment as illustrated in FIGS. 2 and 3, the surface 184 ofthe attachment layer 180 may extend along the surface 152 of the chip150, and have an inner edge surface 185 extending from the surface 162to the surface 152 that defines a second opening 186 in the layer 180.Referring to FIGS. 2 and 4A, the second opening 186 may overlie theopening 124A, and a portion 188 of the opening 186 may extend beyond theedge 160 of the chip 150A in the direction L1. The portion 188 of theopening 186 desirably extends from, and is in fluid communication with,the portion 125. In addition, the second opening 186 extends from, andis in fluid communication with, the opening 124A along portions of theopening 124A that the chip 150A overlies. The opening 186 desirablyextends to portions of the surface 152 including the contacts 156, andmay have dimensions that extend in the directions L1 and L2 co-extensivewith the dimensions of the opening 124A. The attachment layer 180 mayalso extend along portions of the surface 114 of the substrate 112uncovered by the chips 150, as shown in FIG. 4A. In an alternativeembodiment, the attachment layer 180 may be disposed only between thesurface 152 of the chips 150, such as the chip 150A, and the surface 114of the substrate 112, as shown in FIG. 4B.

At the stage of manufacture of the assembly 100 shown in FIG. 2, thesurface 152 of the chip 150A, the substrate 112 and the attachment layer180, in combination, define a bond channel window 195 formed from theopenings 124A and 186, including the portions 125 and 185, and thewindow 195 is in fluid communication with an environment at the surface114 side or top side of the substrate 112 only at the portions 125 and188. In other words, the bond channel window 195 is in fluidcommunication with the environment at top side of the substrate 112 onlythrough the portions 188 and 125.

Referring again to FIG. 2, the opening 124B may be defined by oppositeinner edges 144B′ and 144B″ of the substrate 112 that are spaced fromeach other in the direction L2, and the chip 150B overlies the entiretyof the opening 124B except for portions 165A and 165B of the opening124B that extend beyond the edges 162 and 166 of the chip 150B in thedirection opposite to L2 and in the direction L2, respectively. Inaddition, the attachment layer 180 may define a second opening 187extending from the surface 184 to the surface 186 and to portions of thesurface 152 of the chip 150B including the contacts 156, and havingdimensions that extend coextensive with the dimensions of the opening124B. The opening 187, thus, may extend from, and be in fluidcommunication with, the opening 124B along its length in the directionL2, including the portions 165A and 165B. At the stage of manufacture ofthe assembly 100 shown in FIG. 2, the surface 152 of the chip 150B, thesubstrate 114 and the attachment layer 180, in combination, define abond channel window 197 formed from the openings 124B and 187, includingthe portions 165A and 165B, which is in fluid communication with theenvironment at the top side of the substrate 112 only at the portions165A and 165B. In other words, the bond channel window 197 is in fluidcommunication with the environment on the top side of the substrate onlyat the portions 165 extending beyond the opposite edges 162 and 164 ofthe chip 150B along the direction L2. The openings 187 and 124B may havea dimension extending in the direction L2 having the same length CH(B),which exceeds the length D2. In one embodiment, the portion of theattachment layer 180 defining the opening 187, and hence partiallydefining the window 197, may be disposed only between the chips 150B andthe substrate 112, similarly as shown in FIG. 4B for the chip 150A.

Further, the assembly 100 may include wire leads 190 joining thecontacts 156 at the surface 152 of the chips 150 with pads 122 on thesurface 116 of the substrate 114. For example, referring to FIG. 3, fora chip 150A, the wire lead 190 may extend from the contact 156, throughthe opening 186 and the opening 124A that the chip overlies, to a pad122 on the surface 116. Wire leads similarly may extend from contacts156 of the chips 150B, through the openings 187 and 124B forming therespective windows 197 that the chips 150B overlie, to pads 122 on thesurface 116.

In a further stage of manufacture of the assembly 100 having anin-process structure as shown in FIG. 2, referring to FIGS. 5 and 6 anencapsulant 200 including dielectric material may be formed overlyingthe chips 150, uncovered portions of the surface 184 of the attachmentlayer 180 and uncovered portions of the surface 116, and also in thebond channel windows 195 and 197. In some embodiments, the encapsulant200 may contact the peripheral edges of the chips 150, and includeencapsulation portions 200A and 200B extending through the respectivebond channel windows 195 and 197 that encapsulate portions of thesurface 152 including contacts 156 that overlie the respective bondchannel windows, the wire leads 190, the pads 122 at the surface 116joined with the wire leads 190, and portions of the surface 116extending from the bond channel windows. For ease of description andillustrating the encapsulant portions 200A and 200B, encapsulantmaterial on the surface 184 is not shown in FIG. 5, which is a plan viewof the top side of the substrate.

In some embodiments, the encapsulant portion extends along the entiretyof the elongated dimension of the bond channel windows. For example, theportion 200A may extend in the window 195 from the end 126 to the end128 of the opening 124A, which correspond respectively to the oppositeends of the window 195 in the direction L1. In some embodiments, theencapsulation portion occupies the entirety of the bond channel window,for example, all empty space of each of the openings 124A and 186 thatform the window 195.

In an embodiment of a method of manufacture of the assembly 100, theencapsulant 200 may be formed by flowing encapsulant material, such ascompound EME-X81126 or like dielectric material, at a temperature of175° C. and pressure of 6.9 MPa, from a molding tool (not shown) in thedirection L2 towards the chips 150A and 150B of the assembly 100arranged as shown in FIG. 2, over the top side of the substrate 112,such as along the surface 184 of the attachment layer 180 (see FIG. 4A).At the chip 150A, the flowing encapsulant material may flow into thebond window 195 from the portions 188 and 125, and then continue to flowalong the length of the window 195 from the edge 160 in the directionopposite to L1 towards the end 126 of the window 195. A molding element215 (see FIG. 6, shown in phantom) may be positioned on the surface 116or bottom side of the substrate 112 overlying the window 195, to enclosethe window 195 at the bottom side of the substrate, and have aconfiguration such that a surface 202 of the encapsulant portion 200A isformed remote from a surface 203 of the portion 200A contacting thesurface 152 of the chip 150A. The surface 202 may extend to portions ofthe surface 116 on either side of the bond channel window 195 in thedirection L2 and also in the direction L1, depending on theconfiguration of the molding element 215 and its positioning upon thesurface 116, to define an outer perimeter 207A of the encapsulationportion 200A at the surface 116.

Further, at the chip 150B, the encapsulant material, flowing towards thechip in the direction L2, flows through the bond channel 197 from theportion 165A, then along the length of the channel 197 in the directionL2 and out of the bond channel 197 at the portion 165B, to form theencapsulation portion 200B. The molding element 215 may be positioned atthe bottom side of the substrate 112 during formation of the encapsulant200, similarly as discussed for the chip 150A, to form a surface 202 ofthe encapsulant portion 200B remote from a surface 203 thereofcontacting the surface 152 of the chip 150B. The encapsulation portion200B may extend to the surface 116 on either side of the bond channelwindow 197 in the direction L2 and also in the direction L1, dependingon the configuration and positioning at the surface 116 of the moldingelement 215.

Accordingly, based on the construction of the window 195, theencapsulation material, flowing in the direction L2 toward the chip150A, may flow into the window 195 only at the portions 125 and 188, andmaterial flow therefrom away from the edge 160 of the chip is in thedirection opposite to L1 and through a portion of the window 195 whichis not in fluid communication with the environment at the top side ofthe substrate, and which may be enclosed at the bottom side by themolding element 215 so as not to be in fluid communication with theenvironment at the bottom side of the substrate. Encapsulation materialflow from the top side of the substrate into the window 195 in thedirection L1 cannot occur. The configuration of the window 195, thus,advantageously provides that, during flow of encapsulation materialtoward the chip 150A in a direction transverse, such as orthogonal, tothe elongated dimension of the window 195, the encapsulant material canflow into the window 195 only at the end 128 thereof, in other words,flow from either end of the elongated opening as in the prior art (seeFIG. 1) cannot occur, such that flow through the window 195 from the end128 is only in a single direction, which may avoid formation of airpockets or voids in the window 195. In one embodiment, the dielectricmaterial may be flowed over the top side of the substrate for tenseconds, after which the material may be cured for 90 seconds to formthe encapsulant 200.

In another aspect, a microelectronic assembly may include chips 150Boverlying bond channel windows 197, similarly as described for theassembly 100, chips 150A, having a configuration similar to thatdescribed above for the assembly 100, overlying respective bond channelwindows extending elongated in a transverse direction to the windows197, and an outlet or vent extending from and in fluid communicationwith the windows that the chips 150A overlie. As discussed below, thevents may be configured to permit air within the window to exit thewindow into the vent when encapsulant material is flowed through thewindow to form an encapsulant portion in the window. The vent may bepartially defined by a structure that overlies a surface of thesubstrate and a portion of such surface of the substrate.

In one embodiment of a microelectronic assembly including a ventaccording to the disclosure, referring to FIGS. 7-9, a microelectronicassembly 500 may include chips 150B overlying bond channel windows 197formed by a substrate 514 and an attachment layer 580 and extendingelongated in a direction L2, similarly as described for the assembly100. In addition, the assembly 500 may include the chips 150A overlyingrespective bond channel windows 400 formed by the substrate 514 and theattachment layer 580 and extending elongated in a direction L1. Further,the assembly 500 may include, at each window 400, a vent 600A extendingfrom and in fluid communication with the window 400, and partiallydefined by the substrate 512. The vent 600A extends beyond a peripheraledge 159 of the chip 150A, which extends between the edges 158 and 160,to a portion 602 of the vent 600A at which the vent 600A is in fluidcommunication with an environment at a top side of the substrate 512during a stage of manufacture of the assembly 500. The portion 602 ofthe vent 600A, hence, may provide that the window 400 is in fluidcommunication with the environment at the top side of the substratethrough the vent 600A during manufacturing operations of the assembly500, which may avoid entrapment of air in the window 400 whenencapsulant is provided to form an encapsulant portion in the 400 windowas described in detail below.

Referring to FIGS. 8 and 9, in one embodiment the assembly 500 mayinclude the substrate 512 defining an opening 524A that extends from afirst surface 514 to an opposite second surface 516 of the substrate 512and has an elongated dimension extending a length CH(C) in a directionL1 from a first end 526 to an opposite second end 528 of the opening524A. The opening 524A is defined by opposite inner edge surfaces 544′and 544″ of the substrate 512 at the ends 526 and 528, respectively,that are spaced from each other the length CH(C) in the direction L1.The chip 150A overlies the opening 524A except for portions 565A and565B of the opening 524A that extend beyond the edges 158 and 160 of thechip 150A in the direction opposite to L1 and in the direction L1,respectively, to the edge surfaces 544′ and 544″.

In addition, the assembly 500 may include an attachment layer 580 havingan inner surface 585 extending from a surface 582 to a surface 584opposite the surface 582. The inner surface 585 defines a second opening586 extending to portions of the surface 152 of the chip 150A includingthe contacts 156, and having an elongated dimension extending in thedirection L1 coextensive with the elongated dimension of the opening524A. The opening 586 desirably extends from, and is in fluidcommunication with, the opening 524A, including the portions 565A and565B. In one embodiment, the opening 586 has dimensions in thedirections L1 and L2 coextensive with respective dimensions of theopening 524A. Similar to the assembly 100, a bond channel window 595 maybe formed from the openings 524A and 586, including the portions 565Aand 565B that extend beyond the edges 160 and 158, respectively.

The chip 150A may include opposite peripheral edges 159A and 159Bextending between the edges 158 and 160. In the illustrated embodiment,the chip 150A may have a rectangularly-shaped periphery, where the edges158 and 160 are parallel and orthogonal to the edges 159, and overliethe substrate 512 with the edges 158, 160 extending in the direction L2and the edges 159 extending in the direction L1, which is orthogonal toL2.

In one embodiment as shown in FIGS. 7-9, the vent 600A may be defined bya surface portion 514′ of the surface 514 of the substrate 512 extendingfrom an inner edge surface 544A of the substrate that defines the window524A. The inner edge surface 544A is disposed between the inner edgesurfaces 544′ and 544″ of the substrate 514, and the surface portion514′ extends from the inner edge surface 544A to an inner surface 581 ofthe attachment layer 580. The inner surface 581 extends from the surface582 to the surface 584, and from an inner surface 583 to an innersurface 587 of the attachment layer 560 which is opposite the surface583. The inner surfaces 583 and 587 extend from the surface 582 to thesurface 584 of the attachment layer, and also in the direction L2 fromthe surface 585 to the surface 581. In addition, the surface portion514′ extends from the surface 583 to the surface 587 of the attachmentlayer 580. Further, a portion 157A of the surface 152 of the chip 150Aoverlies a surface portion 514′A of the surface portion 514′ to define,in combination with the surface 584 of the attachment layer 580, aninterface 604 of the portion 602 of the vent 600A which overlies asurface portion 514′B of the surface 514′. The surface portions 514′Aand 514′B, which are distinct surface portions, together form thesurface portion 514′. The interface 604 extends in the direction L2 fromthe surface 157A at the edge 159A of the chip 150A to the portions ofthe surface 584 from which the surfaces 581, 583 and 587 extend towardthe surface 582.

In one embodiment, the interface 604 may have surface area of about atleast 10,000 square micrometers. In addition, the vent portion 602 mayhave a dimension extending in the direction L1 from the edge 583 to theedge 587 of between about 200 and 300 micrometers, and a dimensionextending beyond the edge 159 in the direction L2 of at least about 50to 300 micrometers. In addition, the vent 600A, at the surface 585, mayhave a dimension extending in the direction L1 from the edge surface 583to the edge surface 587 of between about 200 and 300 micrometers. Inanother embodiment, the vent 600A may extend from the window 400 to aperipheral edge 501 of the assembly 500.

At this stage of manufacture of the assembly 500 (FIG. 8), the surface152 of the chip 150A, the surface 544 of the substrate 512 and thesurface 585 of the attachment layer 580, in combination, define a bondchannel window 595 formed from the openings 524A and 586, including theportions 565A and 565B, which is in fluid communication with anenvironment at the top side of the substrate 512 at the portions 565Aand 565B through the vent 600A. The vent 600A is defined by the surfaces581, 583 and 587 of the attachment layer 580, the surface portion 514′of the substrate and the surface portion 157A of the chip 152A. The bondchannel window 595 is in fluid communication with the environment on thetop side of the substrate at the portions 565 extending beyond theopposite edges 158 and 160 along the direction L1, and through the vent600A, which is in fluid communication with the environment on the topside of the substrate at the interface 604 of the vent portion 602.

In one embodiment, the chip 150A may overlie the window 595 and notoverlie the vent 600A, such that vent 600A is defined only by thesurface 514′ and an inner surface or surfaces, such as the surfaces 581,593 and 587, of the attachment layer 580.

Similar to the assembly 100, wire leads 190 may extend from the surface152 of the chip 150A, through the opening 586 and the opening 524A, totraces 522 on the surface 516. Also, wire leads 190 may extend fromcontacts of the chips 150B through the openings forming the bond channelwindow 197 to traces on the surface 516, similar as in the assembly 100.

In a further stage of manufacture of the assembly 500 having anin-process structure as shown in FIGS. 7-9, an encapsulant 700 includingdielectric material may be formed overlying the chips 150, uncoveredportions of the surface 584 of the attachment layer 580 and uncoveredportions of the surface 514 and the surface 516; and in the bond channelwindows 197 and 595 and, optionally, in the vents 600A, as shown inFIGS. 10-11. For ease of description and illustrating encapsulantportions 700A and 700B in the bond channel windows 197 and 595,encapsulant material on the surface 584 is not shown in FIG. 10.

In some embodiments, the encapsulant 700 may include an encapsulationportion 700B, configured similar to the portion 200B in the assembly100, extending through the bond channel window 197 to encapsulateportions of the surface 152 including contacts 156, the wire leads 190,traces 522 at the surface 516 joined with the wire leads, and portionsof the surface 516 extending from the bond channel window 197 to aperimeter edge 707B of a surface 702B of the portion 700B remote fromthe chip 150B.

In addition, the encapsulant 700 may include an encapsulation portion700A extending through the bond channel window 595, to encapsulateportions of the surface 152 including contacts 156, the wire leads 190and traces 522 at the surface 516 joined with the wire leads. Inaddition, the encapsulation portion 700A may overlie uncovered portionsof the surface 516 extending from the window 595 to uncovered portionsof the surface 516 and include a surface 702A remote from the chip 150A.The surface 702A may extend to portions of the surface 516 on eitherside of the bond channel window 195 in the direction L2 and also in thedirection L1 to define an outer perimeter 707A of the encapsulationportion 700A at the surface 516.

In addition, the encapsulant portion 700A may extend into the vent 600Aand to the interface 604 of the vent portion 602, and in some embodimentfill the entirety of the vent 600A.

In an embodiment, the encapsulant 700 may be formed by flowingencapsulant material from a molding tool (not shown) in the direction L2towards the chips 150A and 150B, such as arranged as shown in FIGS. 7and 9, over the top side of the substrate 512, such as along the surface584 of the attachment layer 580. At the chip 150B, the encapsulantmaterial flows through the bond channel 197, similarly as describedabove for the assembly 100, and a molding element may be positionedagainst the surface 516 of the substrate 112 to form the surface 702 ofthe encapsulant portion 700B. In addition, referring to FIGS. 10-11, atthe chip 150A the encapsulant material may flow through the bond channelwindow 595, from the portion 565A in the direction opposite to L1 andthe portion 565B in the direction L1, to portions of the window 595 thatthe chip 150A overlies. The flow of the encapsulant material from theopposite ends 526 and 528 of the opening 524A towards each other alongthe elongated dimension of the window 595 may cause air to be forcedfrom the window 595 into the vent 600A, which desirably is apredetermined distance in the direction L1 from an end 526 or 528 of thewindow 595 that is a percentage of the length CH(C). In one embodiment,the vent 600A is a distance equal to about 40-60% of the length CH(C)from either of the ends 528 and 526 of the window 595, so as to providethat when encapsulant is flowed to form the portion 700A air may exitfrom the window 595 at the vent 600A to avoid voids being formed in thewindow 595.

In one embodiment, the encapsulant portion 700A may extend into the vent600A from the window 595 and also from the interface 604 of the portion602. In some embodiments, the encapsulant portion 700A may occupy theentirety of the window 595 and also the vent 600A. The arrangement ofthe window 595 with the vent 600A extending therefrom advantageously maypermit encapsulant material flowing in a transverse, such as orthogonal,direction to the elongated direction in which the window 595 extends, toenter into the channel 595 from both ends 526 and 528 and flow from theends 526 and 528 toward a portion of the window from which the vent 600Aextends so as to force any air in the window 595 into the vent 600A,thereby avoiding air pockets or voids from being formed in the channel595 during flow of encapsulant material to form the encapsulationportion 700A.

In one embodiment, during flow of the encapsulant material to form theencapsulant, a vacuum device 216 (shown in phantom in FIG. 11) thatapplies a vacuum may be positioned at the top side of the substrate nearor at the interface 604. During flowing of encapsulant material to formthe encapsulant portion 700A, the vacuum device 216 may be operated toapply a vacuum at the interface 604 to evacuate air from the window 595,through the vent 600A and the interface 604, and into the vacuum device,which may avoid entrapment of air in the window 595 during formation ofthe encapsulant portion 700A. The interface 604 of the vent portion 602desirably has dimensions that avoid encapsulant material that is flowingalong the top side of the substrate from entering into the vent portion602 through the interface 604.

In another embodiment, referring to FIGS. 12 and 13, a microelectronicassembly 500′ may include chips 150B overlying bond channel windows 197,similarly as described above for the assembly 500. In addition, theassembly 500′ may include chips 150A, having a configuration similar tothat described above for the assembly 500, overlying respective bondchannel windows 595′ defined by the substrate 512, the attachment layer580 overlying the surface 514 of the substrate 512 and a photoimageablelayer 850 overlying the surface 516 of the substrate 512, where thewindow 595′ extends elongated in the direction L1. Further, the assembly500′ may include, at each window 595′, a vent 600A′ defined by thesubstrate 512 and the layer 850 and extending from the window 595′, andwhich is in fluid communication with an environment at the surface 516of the substrate 512 during a stage of manufacture of the assembly 500′.In one embodiment, the vent 600A′ may extend from the window 595′ beyonda peripheral edge of the chip 150A, such as the edge 159A of theoverlying chip 150A.

In the illustrated embodiment, the chip 150A overlies the attachmentlayer 580 and the attachment layer 580 forms the opening 586 havingdimensions in the directions L1 and L2 co-extensive with respectivedimensions of the opening 524A, as in the assembly 500. In addition, thephotoimageable layer 850, such as a solder mask layer, may be formed onportions of the surface 516 to uncover surface portions 517 of thesurface 516 and traces 522 on the surface 516. The layer 850 extendsfrom a surface 852 extending along the surface 516 to a surface 854opposite the surface 854. The layer 850 may include an inner surface885, which extends from the surface 852 to the surface 854 and definesan opening 824. The opening 824 may extend from, and be in fluidcommunication with, the opening 524A along the elongated dimensionextending in the direction L1. In one embodiment, the opening 824 hasdimensions extending in the directions L1 and L2 co-extensive withrespectively corresponding dimensions of the opening 524A. Thecombination of the openings 524A, 586 and 824 form a bond channel window595′.

The uncovered surface portions 517 may be configured by the layer 850 sothat solder elements 690, such as solder balls, may be formed at theportions 517 in a pattern as a solder ball grid array, usingconventional techniques.

In addition, an uncovered surface portion 517′ of the surface 516 mayextend in the direction L2 from the inner edge 544A of the substrate 516that defines the window 524A. The surface portion 517′ extends from theinner edge 544A to an inner surface 881 of the layer 850, which extendsfrom the surface 582 to the surface 584, and from an inner surface 883to an inner surface 887 of the layer 850 opposite the surface 883. Theinner surfaces 883 and 887 extend from the surface 852 to the surface854 of the layer 850, and also from the surface 885 to the surface 881in the direction L2. In addition, the surface portion 517′ extends fromthe surface 883 to the surface 887 of the layer 858. The surface portion517′, in combination with the surfaces 881, 883 and 886 of the layer850, defines a vent 600A′ at the bottom side of the substrate 512.

In one embodiment, the surface area of the portion 517′, which isuncovered at the bottom side of the substrate 512, may be about 50,000square micrometers, and may have a dimension extending in the directionL1 from the surface 883 to the surface 887 of about 100 micrometers, anda dimension extending from the surface 885 to the surface 881 in thedirection L2 of at least about 500 micrometers. In other embodiments,the portion 517′ may extend to a peripheral edge 501′ of the assembly500′.

At this stage of manufacture of the assembly 500′, the bond channelwindow 595′ is in fluid communication with an environment at the topside of the substrate 514 at the portions 565A and 565B. In addition,the vent 600A′ is in fluid communication with the bond channel window595′. Also, the vent 600A′ and a portion 597′ of the window 595′ remotefrom and opposite the chip 150A are in fluid communication with theenvironment at the bottom side of the substrate 512.

In one embodiment, the chip 150A may overlie the window 595′ and notoverlie the vent 600A′. Wire leads 190 may extend from the contacts 156at the surface 152 of the chip 150A, through the opening 586, theopening 524A and the opening 824, to traces 522 on the surface 516.

In a further stage of manufacture of the assembly 500′ having anin-process structure as shown in FIGS. 12-13, an encapsulant 900including dielectric material may be formed (see FIGS. 14-15) overlyingthe chips 150, uncovered portions of the surface 584 of the attachmentlayer 580, uncovered portions of the surface 516 and uncovered portionsof the surface 854 extending from the window 595′; and in the bondchannel windows 197 and 595′ and, optionally, in the vents 600A′. Theencapsulant 900 includes encapsulant portions 900B in the bond channelwindows 197, similar to the encapsulant portions 700B in the windows 197as in the assembly 500.

In addition, the encapsulant 900 may include an encapsulation portion900A, extending through the bond channel window 595′, to encapsulateportions of the surface 152 including contacts 156, the wire leads 190and the traces 522 at the surface 517 joined with the wire leads. Inaddition, the encapsulation portion 900A may overlie uncovered portionsof the surface 854 extending from the bond channel window 595′ andinclude a surface 902A remote from the chip 150A extending from theuncovered portions of the surface 854 adjacent the window portion 597′.The surface 902A may extend to portions of the surface 854 on eitherside of the bond channel window 595′ in the directions L2 and L1 todefine an outer perimeter 907A of the encapsulation portion 900A at thesurface 854.

In addition, the encapsulant portion 900A may extend into the vent 600A′and to the surface 881 of the layer 850 and the surface portion 517′,and in some embodiments fill the entirety of the vent 600A′.

In an embodiment, the encapsulant 900 may be formed by flowingencapsulant material from a molding tool (not shown) in the direction L2towards the chips 150A and 150B, such as arranged as shown in FIG. 12,over the top side of the substrate 512, similarly as described above forthe assembly 500. The encapsulant portions 900B may be formed similarlyas the encapsulation portions 700B in the assembly 500. In addition, atthe chip 150A, the encapsulant material may flow through the bondchannel window 595′, from the portions 565A and 565B similarly asdescribed for the assembly 500. In this embodiment, however, the flow ofthe encapsulant material from opposite ends of the window 595′ may causeair to be forced from the window 595′ into the vent 600A′ at the bottomside of the substrate, such that the encapsulant portion 900A is formedin the window 595′ without voids and completely encapsulates the leads190 and contacts at the surface 152 of the chip.

In some embodiments, the encapsulant 900A may occupy the entirety of thewindow 595′ and also the vent 600A′. The arrangement of the window 595′with the vent 600A′ extending therefrom advantageously may permitencapsulant material flowing in a transverse, such as orthogonal,direction to the direction that the window 595′ extends elongated, toenter into the channel 595′ from opposite ends of the elongateddimension and then flow toward a portion of the window from which thevent extends and force air in the window 595′ into the vent 600A′,thereby avoiding air pockets or voids from being formed in the channel595′ during flow of encapsulant material.

In one embodiment, when the encapsulant material is flowing over the topsurface of the substrate, the molding element 215 may be positionedagainst the bottom surface of the substrate 516 and a vacuum device 216′may be positioned at the bottom side of the substrate at the vent 600A′.The vacuum device 216′ may be operated to apply a vacuum at the vent600A′ to evacuate air in the window 595′ through the vent 600A′ into thevacuum device 216′, which may then exhaust the evacuated air to theenvironment.

In one embodiment, an assembly according to the disclosure may include avent formed from a first vent, such as vent 600A, at the top side of thesubstrate and a second vent, such as a vent 600A′, also at the bottomside of the substrate as described above for the assemblies 500 and500′, respectively. In another embodiment, the one or more vents mayextend from a bond channel window, such as the window 595 or 595′,beyond a peripheral edge of the chip 150A between the edges 158 and 160.

FIG. 16 is a plan view of a bottom side of a substrate of amicroelectronic assembly 950 according to another embodiment of thedisclosure. Referring to FIG. 16, the microelectronic assembly 950 mayinclude chips 150B and 150A arranged overlying bond channel windows 197and 595′, respectively, similarly as in the assembly 500′ (see FIGS.12-15), and a plurality of vents 952 formed at the bottom side of thesubstrate 512 and extending from the windows 595′, similar to the vents600A in the assembly 500′. In one embodiment, a chip 150A′ may haveopposite peripheral edges 159A and 159B that extend from the edge 158and 160, and the layer 850 may include inner surfaces 885A and 885B thatextend in the direction L1 and define the window 595′. Vents 952′ mayextend from the window 595′ that a chip 150A′ overlies, in the directionL2, beyond the peripheral edge 159A of the chip 150A to a peripheraledge 951 of the assembly 950. The layer 850 may be configured on thesurface 516 of the substrate 514 such that the vents 952′ extend fromthe surface 885B in the direction L2 and between solder elements 690that the chip 150A′ may or may not overlie.

In some embodiments, the layer 850 may be configured on the surface 516such that vents 952″ extend from inner surface 885A of the layer 850defining the window 595′ that a chip 150A″ overlies, in a directionopposite to L2, beyond a peripheral edge 159B of chip 150A″. The vents952 may extend from the window 595 at a position that is distance ofabout 40 to 60% of the length of the window 595′ in the direction L1. Insuch embodiment, during flow of encapsulant material in the directionL2, similarly as described above for the assembly 500′, encapsulant mayflow into the window 595′ from opposite ends thereof, and the vents 952,which extend in the same or the opposite direction to the direction L2that encapsulant flow towards the chips 150A, may avoid entrapment ofair or formation of voids in the windows 595′.

FIG. 17 is a plan view of a top side of a substrate of a microelectronicassembly 1000 according to another embodiment of the disclosure.Referring to FIG. 17, the microelectronic assembly 1000 may includechips 150A and 150B arranged overlying bond channel windows 195 and 197,respectively, similarly as in the assembly 100 (see FIGS. 2-3), andvents 1002 may be formed at the top side of the substrate. For example,similarly as in the assembly 500 (see FIG. 8), the assembly 1000 mayinclude an attachment layer 584 configured to define, with the surface514 of a substrate 512 as shown in FIGS. 8-9, a vent 1002 extending inthe direction L2 from the window 195 adjacent the end 126. The window195, as in the assembly 100, is in fluid communication only at the end128 (portions 125 and 188) with the environment at the top side of thesubstrate 512. The vent 1002 desirably extends in the direction L2 fromthe inner surface 585 of the layer 580 and is at least a distance fromthe end 128 of at least about 90 percent of the length of the window 195in the direction L1. In such embodiment, during flow of encapsulantmaterial in the direction L2, similarly as described above, encapsulantmay flow into the window 195 only from the end 128 at the portions 188and 125 (as discussed with reference to FIGS. 5 and 6) and theencapsulant flowing therefrom in the direction opposite to L1 along theelongated dimension of the window 195 towards the end 126 may force airtowards and into the vent 1002 at the end 126, thereby avoidingentrapment of air or formation of voids in the window 195.

FIG. 18 is a plan view of a bottom side of a substrate of amicroelectronic assembly 1100 according to another embodiment of thedisclosure. The assembly 1100 may include chips 150A and 150B arrangedoverlying windows 195 and 197, similar to the assembly 1000, except thatthe vents 1002 are omitted. In such embodiment, a photoimageable layer850 (see FIGS. 12-13) may be formed on the surface 116 of substrate 112,similarly as on the surface 516 of the substrate 512 in the assembly 500(see FIG. 11), and configured to define vents 1102. The vents 1102 atthe bottom side of the substrate 112 extend from the windows 195,similar to the vents 600A′ in the assembly 500′. The vents 1102 extendgenerally in the direction opposite to L1 at the end 126 of the window195, to a peripheral edge 1101 of the assembly 1100. The layer 850 maybe configured such that vents 1102 include a first portion 1102Aextending at an angle relative to the direction opposite to L1, and asecond portion 1102B extending from the first portions 1102A in thedirection opposite to L1, where the angle of the portion 1102A is toprovide that the portion 1102B extends between adjacent rows of thesolder elements at the surface 116 side of the substrate 112. In suchembodiment, during flow of encapsulant material in the direction L2,similarly as described above for the assembly 500′, encapsulant may flowinto the window 195 from the end 128 in the opposite direction to L1.The vents 1102, which extend from the end 126 in the same direction asthe flow of the encapsulant toward the end 126 from the end 128, mayprovide that entrapment of air or formation of voids in the window 195is avoided, because air may be forced by the flowing encapsulant intovents 1102 from the windows 195. In some embodiments, as described inabove embodiment, a vacuum may be applied at the vents 1102 on thesurface 116 side of the substrate 112 to evacuate air from the window195 through the vents 1102. In one embodiment, the molding tool may beconfigured such that the vent portions 1102A extend throughencapsulation material to the peripheral edge 207A of the encapsulationportion 200A formed in the window 195, and the vent portion 1102Bextends from the surface 202 of the encapsulation element 200A.

In another embodiment, referring to FIGS. 19-21, a microelectronicassembly 1200 may include chips 150A and 150B arranged overlyingrespective bond channel windows formed from openings defined by asubstrate 514 and an attachment layer 580, similarly as in theassemblies 100 and 500 described above, and vents 1210 extending fromthe bond channel windows that the chips 150A overlie. The vents 1210 maybe enclosed at all portions other than an interface 1240 from which thevents 1210 extend from the windows. In other words, the vents 1210constitute an outlet from the windows that does not serve as an exhaustpathway, such as to the environment at the top side of the substrate514, but rather the vents 1210 are volumes of completely enclosed andsealed space except for at the interface 1240 where the vent 1210 is influid communication with the window.

Referring to FIG. 19, chips 150B may overlie bond channel windows 197formed similarly as shown in FIG. 10 for the assembly 500, a chip150A(1) may overlie a bond channel window 1205 and a chip 150A(2) mayoverlie a bond channel window 195 formed similarly as in the assembly100. Referring to FIGS. 20 and 21, the substrate 512 may define anopening 524A, and the attachment layer 580 may define an opening 586having dimensions in the direction L1 and L2 co-extensive with theopening 524A, similarly as in the assembly 500. The opening 524A andopening 586, in combination, form a bond channel window 1205 extendingfrom the end 526 to the end 528 in the direction L1.

The vent 1210-1 may be defined by an inner surface of the attachmentlayer 580, a portion of the surface 514 and a portion of the surface 157of the chip 150(A)1. For example, the vent 1210-1 may defined by aportion 515 of the surface 514 of the substrate 512 extending from theinner edge surface 544A of the substrate that defines the window 524A.The surface portion 515 extends from the inner edge 544A to an innersurface 595 of the attachment layer 580. The inner surface 595 extendsfrom the surface 582 to a portion of the surface 584 that extends alongthe surface 152 of the chip 150A. The inner surface 595 also may extendarcuately from an edge 585′ of the surface 585 to an edge 585″ of thesurface 585, where the edge 585″ is further from the end 526 than theedge 585′. The configuration of the inner surface 595 defines anindentation or recess 1220 in the attachment layer 580. The indentation1220 is bounded by the surface portion 515, a portion of the surface152A which overlies the surface portion 515 and the inner surface 595 soas to define the vent 1210-1 extending at the interface 1240 from thewindow 1205. In another embodiment, the attachment layer may beconfigured to have several inner surface portions extending from oneanother between the edges 585′ and 585″ that form the indentation 1220.In one embodiment, the vent 1210 may have a volume of at least about2,000,000 cubic micrometers, and a dimension of about 40,000 squaremicrometers at the interface 1240.

In some embodiments, a plurality of vents 1210-1 may be formed along theelongated length of the window 1205 and be spaced from the ends 526 and528 similarly as the vents 600A, on either side of the window in thedirection L2.

In addition, a vent 1210-2 extending from the window 195, having aconfiguration similar to the vent 1210-1, may be defined by theattachment layer 580, the surface 157 of the chip 150A(2) and thesurface 514 of the substrate and extend from the window 195 adjacent theend 126. The vent 1210-1, or a plurality of such vents, may bepositioned similarly extending from the window 195 as the vents 1002 inthe assembly 100.

Referring to FIGS. 19 and 20, during flow of encapsulant in thedirection L2, similarly as described for the assembly 500′, at the chip150A(1) the encapsulant material may flow through the bond channelwindow 1205, from the portions 565A and 565B, and cause air to be forcedfrom the window 1205 into the vent 1210-1, such that the encapsulant maybe formed in the window 1205 without voids. In addition, at the chip150A(2) the encapsulant material may flow through the bond channelwindow 195, similarly as in the assembly 100, and cause air to be forcedfrom the window 195 into the vent 1210-2, such that the encapsulant maybe formed in the window 195 without voids and the forced air iscontained in the vent 1201-2.

FIGS. 22 and 23 illustrate another embodiment of a microelectronicassembly 1300 according to the disclosure. The assembly 1300 may includechips 150B arranged overlying windows 197 and chips 150A(1) and 150A(2)overlying windows 1205 and 195, respectively, similar to the assembly1100, except that the vents 1210 are omitted. In such embodiment,photoimageable layer 850 may be formed on the surface 516 of thesubstrate 512 (see FIG. 11), and configured to define, with portions ofthe surface 516 of the substrate, vents 1310 extending from the windows1205 and 195 at the bottom side of the substrate. For example, the vent1310-1 may be defined by a surface portion 517″ of the surface 517extending from the surface 585 towards an inner surface 881′ of thelayer 850. The surface 881′ may have a configuration similar to thesurface 595 in the assembly 1200, to define a recess in the layer 850extending from an interface 1330 at the window 1205. The vent 1310-1 mayextend from the interface 1330 at the window 1205 between the ends 526and 528, at a similar position along the length of the window as thevent 1210-1. In addition, a vent 1310-2 may extend from the window 195at the end 126 at a similar position with respect to the opposite end ofthe window 195 as the vent 1210-2. The interface 1330 may havedimensions of at least about 40,000 square micrometers, so as to permitflow of air therethrough while avoiding flow of encapsulant materialtherethough.

Referring to FIG. 22, during flow of encapsulant in the direction L2,similarly as described for the assembly 1100, at the chip 150A(1) theencapsulant material may flow through the bond channel window 1205, fromthe portions 565A and 565B, and cause air to be forced from the portionsof the window 1205 into the vent 1310-1 through the interface 1330, suchthat the encapsulant portion may be formed in the window 1205 withoutvoids. In addition, at the chip 150A(2) the encapsulant material mayflow through the bond channel window 195, similarly as in the assembly1100, and cause air to be forced from the window 195 into the vent1310-2, such that the encapsulant may be formed in the window 195without voids. The molding element 215 may have a configuration suchthat, when positioned at the bottom side of the substrate on the surface854 of the layer 850, the molding element 215 extends beyond the vents1310. When encapsulant material is flowed with the mold element 215positioned in such manner, the vents 1310 are enclosed at the bottomsurface during flow of encapsulant material to flow the encapsulant. Inother words, as shown in FIG. 23, the vents 1310 may be enclosed by themold element 215 and, therefore, the vents 1310 are not in fluidcommunication with the environment at the bottom side of the substrateduring flowing of encapsulant material.

In another embodiment, the encapsulation portion formed in the windowmay extend at least partially into the vents 1210 or 1310.

The assemblies discussed above may be utilized in construction ofdiverse electronic systems. For example, a system 1400 (FIG. 24) inaccordance with a further embodiment of the invention includes a firstpackage assembly 1402, such as containing the encapsulated chip 150A ofthe assembly 100, and a second package assembly 1404, such as containingthe encapsulated chip of the assembly 500, and in conjunction with otherelectronic components 1408 and 1410. In the example depicted, component1408 is a semiconductor chip whereas component 1410 is a display screen,but any other components may be used. Of course, although only twoadditional components are depicted in FIG. 24 for clarity ofillustration, the system may include any number of such components.Package assemblies 1402 and 1404 and components 1408 and 1410 aremounted to a common housing 1401, schematically depicted in brokenlines, and are electrically interconnected with one another as necessaryto form the desired circuit. In the exemplary system shown, the systemincludes a circuit panel 1407 such as a flexible or rigid printedcircuit board, and the circuit panel includes numerous conductors 1409,of which only one is depicted in FIG. 24, interconnecting the componentswith one another. An off-board connector connects component 1410 to thecircuit panel. However, this is merely exemplary; any suitable structurefor making electrical connections may be used. The housing 1401 isdepicted as a portable housing of the type usable, for example, in acellular telephone or personal digital assistant, and screen 1410 isexposed at the surface of the housing. Again, the simplified systemshown in FIG. 24 is merely exemplary; other systems, including systemscommonly regarded as fixed structures, such as desktop computers,routers and the like may be made using the packages discussed above.

As these and other variations and combinations of the features discussedabove may be utilized without departing from the present invention, theforegoing description of the preferred embodiments should be taken byway of illustration rather than by way of limitation of the invention asdefined by the claims.

1. A microelectronic assembly comprising: a substrate having an openingextending between first and second oppositely facing surfaces of thesubstrate, the opening elongated in a first direction; and at least onemicroelectronic element having a front face facing and attached to thefirst surface of the substrate and a plurality of contacts at the frontface overlying the opening, the microelectronic element having first andsecond opposite peripheral edges extending away from the front face,wherein the first peripheral edge extends beyond, or is aligned in thefirst direction with, an inner edge of the opening, and wherein theopening extends beyond the second peripheral edge.
 2. The assembly ofclaim 1 further comprising: an encapsulant contacting at least thesecond peripheral edge, wherein the encapsulant extends through theopening beyond the second peripheral edge and overlies at least aportion of the front face of the microelectronic element.
 3. Theassembly of claim 2, wherein the encapsulant extends through the openingto the first peripheral edge and the front face of the microelectronicelement.
 4. The assembly of claim 2, wherein the encapsulant occupiesthe opening in its entirety.
 5. The assembly of claim 2, wherein theencapsulant contacts the first surface and at least another portion ofthe microelectronic element.
 6. The assembly of claim 1 furthercomprising: an attachment layer attaching the first surface of thesubstrate with the front face of the microelectronic element, theattachment layer defining a second opening extending beyond the secondperipheral edge and from the opening in the substrate to at least aportion of the front face.
 7. The assembly of claim 6 furthercomprising: an encapsulant contacting at least the second peripheraledge, wherein the encapsulant extends through the opening and the secondopening beyond the second peripheral edge and overlies at least aportion of the front face of the microelectronic element.
 8. Theassembly of claim 7, wherein the encapsulant extends through the openingand the second opening to the first peripheral edge and the front faceof the microelectronic element.
 9. The assembly of claim 1 furthercomprising: a second microelectronic element having a front face facingand attached to the first surface of the substrate, the secondmicroelectronic element overlying a second opening extending between thefirst and second surfaces of the substrate and having a plurality ofcontacts at the front face thereof overlying the second opening, thesecond microelectronic element having third and fourth oppositeperipheral edges, wherein the second opening extends beyond the thirdand fourth peripheral edges, and wherein a first line extending from thethird peripheral edge to the fourth peripheral edge is transverse to asecond line extending from the first peripheral edge to the secondperipheral edge.
 10. The assembly of claim 1, wherein the first andsecond lines are orthogonal to each other.
 11. The assembly of claim 1,wherein the opening extends beyond the second peripheral edge about 150micrometers.